New Guy

Discussion on Stirling or "hot air" engines (all types)
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FlyWheel
Posts: 6
Joined: Thu Jan 14, 2016 3:04 pm

New Guy

Post by FlyWheel » Thu Jan 14, 2016 3:36 pm

Hey All

Have finally retired and have the time to do something I have long wanted to do which is build
an engine(s). Have been working with one of the common ebay Stirling Gamma models. I have learned
a lot from this little model and enjoyed it enough to start a build from the Boydhouse plans.

I'm through the metal working part and am now down to making the wood parts. The build has
gone pretty smoothly thus far.

I have started thinking on a larger engine to the point of gathering materials, which will probably be a flame licker.
Can they be discussed here?

Would also like to build a large Stirling.

Ian S C
Posts: 2221
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: New Guy

Post by Ian S C » Fri Jan 15, 2016 3:20 am

FlyWheel, yes flame lickers are spot on. What sort of workshop equipment do you have, ie., lathe etc?
Ian S C

FlyWheel
Posts: 6
Joined: Thu Jan 14, 2016 3:04 pm

Re: New Guy

Post by FlyWheel » Fri Jan 15, 2016 7:19 am

Hi Ian SC, Is the SC South Carolina?

I now only have the basic shop tools. With in the last year I have relocated into a much smaller place
and had to give up my lathe. I still have my drill press, metal band saw, and MIG welder.

Am working on a jig to allow basic turning on my drill press. The fact that these engines like loose tolerances
works in my favor for basic machining. I'm an old school hand fabber and can one way or the other build most
basic machines. I wont be able to turn out a beautifully finished piece like the many fabulous engines I have
seen but it should still be pretty nice.

I worked on the flame licker cylinder last night. Its derived from a 2" hydraulic cylinder, a tie rod type. I have several
ideas on how to construct it. One is simply rearranging some of the existing parts. The other is just using the cylinder its self.

I have ordered some 2"x1" 6061 T6 discs cut from lathe bar stock for the piston and 2x2" for the sliding valve. That's about as far as I have
gotten. Am trying to work out a variable timing set up, but haven't hit on exactly what I want to try yet. I also will have to come up with cooling
as the cylinder in finless of course. Leaning toward liquid.

Ian S C
Posts: 2221
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: New Guy

Post by Ian S C » Sat Jan 16, 2016 2:46 am

It's good that you are using hydraulic cylinders for "pre bored" cylinders, another place to get a suitable cylinder is old automobile shock absorbers, once you work out how to get them apart.
Although these motors don't like tight fits, things like pistons must be accurate.
The best metal for pistons is cast iron, it's self lubricating with the free graphite (that's what makes all the mess. Aluminium will work, but has a high co efficient of friction.
Don't give up on having a lathe, there are some quite serviceable mini lathes that would handle most of the work needed except turning a flywheel.
The S C after my Ian stands for Stewart Clark, my middle and last names, New Zealand is about half way round the earth from South Carolina.
Ian S C

FlyWheel
Posts: 6
Joined: Thu Jan 14, 2016 3:04 pm

Re: New Guy

Post by FlyWheel » Sun Jan 17, 2016 6:53 am

Ian SC
I should have caught your location from the text on the right--duh.

For the flame licker I have fabbed the piston from a 2" bar billet. Its .75" in depth. I was pleasantly surprised to find the bar stock fit the
bore perfectly. I had assumed it would be several thousands over size. It has clearance of .0150 and excellent compression dry. I have also
bought two antique 7" cast Iron cart wheels for flywheels. I can run one or both depending on weight needed.

Am trying to come up with a stroke to run. I'm sure there is an ideal ratio. I can run up to 5" or less. If less the unused cylinder behind
the stroke will aid in cooling a bit. Still waiting on the 1.250 bar to make the sliding valve.

My wife does craft shows and I used to take one of my Maytag twins along before both wound up in antique bicycles. They were a real people magnet as soon as started. Would like to do the same with the flame licker and the Stirling. The issue with the flame licker will be wind. will have to come up with a flame shield of sorts. The Stirling is in the last stages of assembly. Hope to run it soon.

Am having trouble loading pics. Am getting "file too large". My camera is on the lowest setting and I am posting pics at several other forums. What am I missing?

Ian S C
Posts: 2221
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: New Guy

Post by Ian S C » Sun Jan 17, 2016 6:24 pm

Flywheel, the clearance should be nearer to .001" for a 2 piston, one way you can over come a larger gap is to use a leather cup seal on the crown of the piston, this has the added advantage of working as a snifter valve, allowing air past it as the piston decends to BDC.
When I post photos I reduce them on the computer, I can Rt click on the pic and reduce to some where about 680 x 420 or some where about that, that size works for most forums.
Another way of getting a fit if a piston is too loose, cut a shallow groove(like a ring groove), and wrap some Teflon plumbers tape around in the groove.
Ian S C

FlyWheel
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Joined: Thu Jan 14, 2016 3:04 pm

Re: New Guy

Post by FlyWheel » Wed Jan 20, 2016 8:06 am

Heres a pic of the rough out of the parts. These are "hand hewn" parts in the raw the will be better finished after drilling, threading etc.

The idea is to use the cylinders end cap as the head and the hydraulic port as the flame port. Since I want to run the engine outdoors
I have the idea that the port should be on the bottom with a shield possibly made from a metal funnel, and fueled from a propane cylinder
through a modified propane torch head. The cylinder will be lapped to the head eliminating the o-ring. Both the valve and piston
will be drilled to lighten some what.

If this doesn't work out I will just run the cylinder with a sliding valve the same size as the piston and cut in a flame port like Ridders design.
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Ian S C
Posts: 2221
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: New Guy

Post by Ian S C » Thu Jan 21, 2016 4:04 am

Here's a photo of one of my flame lickers before I cleaned it up. and upgraded it, it was built to a plan that was in the British magazine "Model Engineer".
Ian S C DSC01027 (640x480).jpg
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FlyWheel
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Re: New Guy

Post by FlyWheel » Fri Jan 22, 2016 8:13 am

Very nice engine ISC! What did you up grade?

I have a Chinese Ridders copy coming. Hoping it will be here by Saturday. Will use for some hands on and maybe basic dimension
like bore/stroke.

I received the antique cast iron cart wheels to use as flywheels. Am intending to run both. From what I can see
the FL engines need a lot of flywheel. I could run them with a single sided crankshaft but will probably run them double sided(on each side of the con rod) which will require building a true crankshaft. I think the wheels will scale nicely to the rest of the engine.
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Ian S C
Posts: 2221
Joined: Thu Dec 02, 2010 5:15 am
Location: New Zealand

Re: New Guy

Post by Ian S C » Sat Jan 23, 2016 3:07 am

I got two wheels similar to yours, at the moment they have ended up on my garden mulcher after its plastic ones died.
I modified the inlet from the 1/4" hole on the left side of the cylinder head, to a 3/8" x 1/4" rectangular hole. The valve is a strip of cast iron 1/2" wide X 1/16" thick.
I,v built a Ridder type motor, have not got it going, one day I might do something with it.

FlyWheel
Posts: 6
Joined: Thu Jan 14, 2016 3:04 pm

Re: New Guy

Post by FlyWheel » Sat Jan 23, 2016 8:49 pm

Didn't get my Chinese engine today, Monday I guess.

Ordered a 5/8 shaft, 1/4" flat stock and flange bearings for the crankshaft. Will remove the seals and grease from the bearings
and lightly oil them for to reduce the friction. Will probably run a 1/2"x.062 wall scrap of 4130 tubing for the connecting rod.
Havent worked the details completely out on that yet. May just use flat stock.

I will post some pics of the crank build when the materials get here.

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